JP2843931B2 - Linear drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear driving device for converting a rotary motion into a linear motion, and in a case where a linear motion is obtained from a feed of a positioning machine tool such as a robot or other rotary motion, a driving screw shaft. The present invention relates to a device for accurately converting the rotation of an object into a linear motion.

[0002]

2. Description of the Related Art Means for converting a rotary motion into a linear motion include:
Various types have conventionally been invented depending on the application, but for example, positioning of a robot or the like, feeding of a machine tool, and the like require considerable accuracy. Conventionally, for example, a feed screw or a ball screw (linear ball unit) has been used as a linear driving device for that purpose. Recently, there has been proposed an apparatus using a threaded driven shaft without using a nut on the driven side.

A) First, the feed screw is configured to linearly move a driven-side nut screwed therewith by rotation of a drive-side screw shaft. And the like. This is relatively easy to manufacture with a simple configuration, is relatively inexpensive, and can achieve considerable accuracy if processed precisely.

[0004] b) a ball screw is interposed a ball between the driving side of the screw shaft and the driven side of the nut, which has changed to wear rolling sliding wear, NC control for the servo motor as a driving source In most cases, this ball screw is used. This has the advantage that the coefficient of friction is extremely low as compared with the feed screw.

C) Further, in the case of using a driven shaft body with a screw on the driven side, a plurality of screw driven shafts rotatably supported by a main body case around a screw rod-shaped drive shaft. Body
It is the one that was screwed in by pressure. This is such that each driven shaft body is rotated by rotation of a drive shaft, and a main body case that supports the driven shaft body can be linearly driven in the axial direction (for example, see Japanese Patent Application Laid-Open No. 5-215196). .

[0006]

However, since the feed screw of the above a) has a large friction coefficient and a large frictional resistance as described above, a specific portion of the screw rod and the nut are easily worn.
There is a problem.

The ball screw of the above b) has a complicated structure and is expensive, and the nut can move only one pitch of the screw thread in one rotation of the driving screw shaft. Can not do.

[0008] Further, in the case of (c) above, in which the driven shaft body with a screw is used on the driven side, the driven shaft body is rotated by the rotation of a screw rod-shaped drive shaft, but the driven shaft body rotates around the drive shaft. Does not revolve. Therefore, depending on the setting state of the moving block connected to the main body case, the load is concentrated on a specific one of the plurality of driven shafts, and only the specific driven shaft is worn quickly and lacks durability. There is a problem.

SUMMARY OF THE INVENTION The present invention aims to solve the above-mentioned problems in the conventional linear drive device. That is, an object of the present invention is to provide a relatively simple configuration, which is excellent in accuracy, can be manufactured relatively inexpensively, can increase the speed of rotation of the drive-side screw shaft into linear movement, and can convert the rotation of the drive-side screw shaft into a specific driven one. without that only shaft wear is concentrated, it is long-term continuous use to improve the resistance to friction耗性is to provide a linear drive.

[0010]

A linear drive device according to the present invention is configured such that a rotating screw-bar-shaped drive shaft 2 is inserted into a cylindrical main body case 1 and press-fitted to the drive shaft 2. A plurality of driven shafts 3 that are rotatable by rotation are rotatably supported by side plates 4 provided on both sides of the main body case 1, and each of the driven shafts 3 has a plurality of annular grooves 5 a. To form a planetary gear portion 8 on the outer periphery of the driven shaft 3 near the side, and an inner gear 9 on the inner periphery of the main body case 1 near the side. The driven shafts 3 can be revolved by press-fitting the planetary gear 8 of each driven shaft 3 with the internal gear 9 of the main body case 1.

In the above configuration, the main body case 1 and the side plates 4 near both sides thereof are relatively rotatable. The pressing screw engagement or the pressing engagement means that the drive shaft 2 and each driven shaft body 3,
This means a state in which each driven shaft 3 and the main body case 1 are screwed or engaged with almost no play.

The drive shaft 2 and each driven shaft body 3 are
May have the same diameter, or one of them may have a large diameter and the other a small diameter. The screw portion of the drive shaft 2 may be a single-thread screw or a multi-thread screw.

The annular groove 5a formed on the outer periphery of each driven shaft 3 is adapted to correspond to the pitch and lead angle of the threaded portion of the drive shaft 2.

[0014]

The operation of the linear drive device according to the present invention is as follows.

A) Around the drive shaft 2 in the main body case 1 as described above, a plurality of driven shafts 3 are
a. When the drive shaft 2 is rotated by a drive motor (not shown), the plurality of driven shafts 3 screwed and pressed are rotated (rotated) accordingly.

Each of the driven shafts 3 has a body case 1 at both ends.
Since the driven shafts 3 are rotatably supported by the side plates 4 closer to both sides, when each of the driven shafts 3 rotates, the rotational force acts as a propulsive force in the axial direction to linearly move the main body case 1 in the axial direction. .
Therefore, if a driven block, for example, a mechanical component is connected to the main body case 1, the component is moved linearly, and the rotary shaft of the drive shaft 2 functions as a linear drive device that changes to a linear motion.

In the above description, when the outer diameter of the drive shaft 2 is D1, and the outer diameter of each driven shaft body 3 press-fitted to the drive shaft 2 is D2, when the former 2 makes one rotation, the latter 3 becomes "D1 / D2".
It will rotate (rotate) by the minute. Therefore, drive shaft 2
If the outer diameter is larger than the outer diameter of each driven shaft body 3 (see FIGS. 1 and 2), the movement distance of the main body case 1 per rotation of the former 2 increases, so that the speed can be increased. Conversely, even if the outer diameter of the drive shaft 2 is smaller than the outer diameter of each driven shaft body 3 (not shown), the movement distance of the main body case 1 per one rotation of the former 2 becomes smaller, but one rotation of the former 2 Since the moving distance of the main body case 1 is added to the above, the speed is also increased.

If the screw portion of the drive shaft 2 is formed as a multi-threaded screw, the moving distance of the main body case 1 per rotation of the drive shaft 2 becomes larger than that of the case of the single-threaded screw.
In this case as well, the speed is increased.

B) On the other hand, in the linear drive device according to the present invention, each driven shaft body 3 not only rotates itself but also revolves by press-fitting with the drive shaft 2. That is, the main body case 1 and each of the plurality of driven shaft bodies 3 are in press-fit engagement with the inner gear portion 9 on the inner side near the side of the former 1 and the planetary gear portion 8 on the outer periphery near the side of the latter 3. .

When each driven shaft 3 rotates by the rotation of the drive shaft 2, each driven shaft 3 is driven along the inner periphery of the main body case 1 by meshing between the gear portions 8 and 9 with the main body case 1. Axis 2
Around the main body case 1 along with the side plate 4 that is rotatable relative to the main body case 1.

As described above, when the outer diameter of the drive shaft 2 is D1 and the outer diameter of each driven shaft body 3 is D2, the latter 3 is expressed as “D2 × π
× D1 / D2 ”. As each of the driven shafts 3 revolves, the load from the driven block connected to the main body case 1 is not concentrated on only one specific driven shaft, and the plurality of driven shafts 3 are sequentially turned on. Will receive it. Therefore wear of the driven shaft member 3 becomes uniform, the lost things like wear faster particular driven shaft body,
Each driven shaft body 3 is so to speak improved resistance to attrition耗性, enables long-term continuous use.

[0022] Moreover, and each of the driven shaft body 3 and the main body case 1,
The planetary gear portion 8 and the internal gear portion 9 are brought into pressure contact engagement with each other.
Since there is almost no rattling or slippage between the driven shafts 3, the revolving of the driven shafts 3 is more reliably performed.

By forcibly stopping the revolving of the driven shafts 3, the driven shafts 3 are less likely to rotate, and the torque can be converted. It is also possible to create a function.

[0024]

FIG. 1, FIG. 2, and FIG. 3 show an embodiment of the linear drive device according to the present invention. A plurality of screw rod-shaped drive shafts 2 that are rotated by a drive motor (not shown)
Here, six driven shafts 3 are screwed into a pressure contact.

That is, a side plate 4 is provided so as to be relatively rotatable near both sides of a cylindrical main body case 1, a drive shaft hole 10 is formed in the center of the side plate 4, and the drive shaft hole 10 is formed in the drive shaft hole 10. Axis 2
Are rotatably and slidably inserted, and six holes 11 for driven shafts are formed here near the outer peripheral portion of the side plate 4, as shown in FIG.
A side portion of each driven shaft body 3 is rotatably supported (rotated) via a bearing 12 in each of the driven shaft body holes 11.

A plurality of annular grooves 5a are formed on the outer periphery of each of the six driven shafts 3, and the annular grooves 5a are screwed into the threaded portions of the drive shaft 2 by press-fitting.

Further, each of the driven shafts 3 and the main body case 1
The planetary gear 8 formed on the outer periphery near the side of the former 3
The internal gear 9 formed on the inner periphery near the side of the body case 1
In addition, each driven shaft body 3 can revolve. This place
In this case, if the drive shaft 2 rotates clockwise as shown in the drawing, each driven shaft
3 also revolves to the right (see FIG. 3) .

The annular groove 5a is formed by a threaded portion of the drive shaft 2.
It is formed so as to correspond to the lead and the lead angle.

The outer diameter of the drive shaft 2 and the outer diameter of the driven shaft 3 may be the same, but if the outer diameter of the drive shaft 2 is larger than the outer diameter of the driven shaft 3 (see FIGS. 1 and 2). In the former 2, the moving distance of the main body case 1 per rotation is increased, so that the speed is increased. Conversely, even if the outer diameter of the drive shaft 2 is smaller than the outer diameter of the driven shaft body 3 (not shown), the former 2 has a smaller moving distance of the main body case 1 per rotation, but the former 2 has one rotation. Since the moving distance of the main body case 1 is added to the above, the speed is also increased in this case.

The screw portion 5 of the drive shaft 2 may be a single-thread screw or a multi-thread screw. In this case, the linear movement is accelerated as compared with the single-thread screw as described above. is there.

Although the side plates 4 in each of the illustrated examples are provided on both outer sides of the main body case 1, the side plates 4 may be provided inside the main body case 1. Needless to say, the number of driven shafts 3 is not limited to six in the embodiment.

[0032]

As is clear from the above, the linear drive device according to the present invention has a relatively simple structure, is excellent in accuracy, can be manufactured relatively inexpensively, and linearly moves the rotation of the drive screw shaft. the accelerated to be converted, and without that certain wear only the driven shaft body is concentrated, it is long-term continuous use to improve the resistance to friction耗性.

That is, the conventional feed screw has a high frictional resistance, and a specific portion of the screw rod and the nut are easily worn. The ball screw has a complicated structure and is expensive, and cannot increase or reduce the linear movement. In the case of using a driven shaft with a thread on the driven side, even if there are multiple driven shafts, the load concentrates on the specific driven shaft at the same location, and only the specified driven shaft is quickly worn. Since it was worn, there was a problem in durability.

On the other hand, the linear drive device according to the present invention
It can be manufactured relatively inexpensively with a simple configuration compared to a conventional ball screw, and can also increase the speed when converting the rotation of the drive shaft into a linear movement. In addition, it is excellent in accuracy and durability as well as the conventional feed screw.

Further, in the linear drive device according to the present invention, a plurality of driven shafts not only rotate but also revolve, as compared with the conventional one using a threaded driven shaft on the driven side. Since each driven shaft receives a load sequentially, and the load is not concentrated only on a specific driven shaft, durability can be improved, and useful effects such as continuous use for a long period of time can be obtained.

[Brief description of the drawings]

FIG. 1 is a partially cutaway longitudinal front view showing an embodiment of a linear drive device according to the present invention.

FIG. 2 is an enlarged longitudinal sectional front view of a main part of the one shown in FIG.

FIG. 3 is a partially cutaway side view of the one shown in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Main body case 2 ... Drive shaft 3 ... Driven shaft 4 ... Side plate 5a ... Annular groove 8 ... Planetary gear part 9 ... Internal gear part 10 ... Drive shaft hole 11 ... Drive shaft hole 12 …bearing

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-58-109758 (JP, A) JP-A-5-215196 (JP, A) JP-A-57-69157 (JP, A) 31740 (JP, B1) Jiko 40-28285 (JP, Y1) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16H 25/20 F16H 25/22 F16H 25/24

Claims (1)

(57) [Claims] 1. A rotating main body case (1).
The screw-shaped drive shaft (2) is inserted through the
A plurality of driven shafts which can be rotated by press-fitting into (2).
(3) Side plates provided on both sides of the body case (1)
The driven shaft (3) is rotatably supported in (4), and each of the driven shafts (3) has a plurality of annular grooves (5
a) is formed and screwed into the drive shaft (2) by press-fitting.
A planetary gear section (8) is formed on the outer periphery near the side of the driven shaft body (3).
And inner teeth near the side of the body case (1)
Planetary gear section of each driven shaft body (3) forming a wheel section (9)
(8) is press-engaged with the internal gear (9) of the main body case (1).
The linear drive device wherein each driven shaft body (3) is capable of revolving .